Friction clutch



NOV 30, 1937. J. 0. ALMEN ET Ar.' 2,100,454

' FRIGTION CLUTCH Filed sept. 28, 193e s Sheets-sheet 1 H Il l Nov. 30,1937. J. o. ALMEN'ET AL FRICTIONv CLUTCH 3 Sheets-Sheet Filed spt.- 28,1956 \\\\\E:E: i Y- Nov. 30, 1937. J. o. ALMEN ET AL 2,100,464

FRICTION CLUTCH Filed Sept. 28, 1956 5 Sheets-Shefet 3 fl Wl Hf? Q"LOAD-LBS.

Patented Nov. 1937 UNITED STATI-:s

FRICTION CLUTCH John 0. Almen, Royal Oak, and Henry J. Kirschner,Detroit, Mich., assignors to General Motors Corporation, Detroit,

Delaware Mich., a corporation of Application September 28, 1936, SerialNo. 102,886

12 Claims.

having a relatively long range of deflection` throughout which thepressures required to produce the deflection change but little, wherebythe clutch action. is not greatly sensitive to excessive 15 facing wear.u

Another and specific object is to make a clutch spring in the form of anannulus formed with radial corrugations progressively decreasing incircumferential extent from its outer to its inner periphery, parts ofthe clutch being received within said corrugations, whereby drivingtorque is transmitted and radial slipping is prevented.

Still other objects associated with the foregoing include the accuratecentering of lthe conventional of loading, simplicity of construction,elimination of frictional losses, red1ction in weight and a lesser costof manufacture.

Fig. 1 is a transverse section through the novel clutch.

Fig. 2 is a view in elevation, partly broken away.

Fig. 3 is a view'of the novel clutch spring in perspective.'

Fig. 4 is a transverse section ci a modified form.

Fig. 5 is a view in elevation of this second form, partly broken away.Fig. 6 is a developed View as seen from line 6- 4o of Fig. 4.- I

Fig. 7 is a similar view fromline'1-1 of Fig. 4.

Fig. 8 is a transverse section through a modified form.

Fig. 9 is a view in elevation, with parts broken away,`of the inventionshown by Fig. 8;

Figs. 10 and 11 are illustrative diagrams.

Referring by numerals to lFigs. 1 to 3 of the drawings, II is the enginecrank shaft-.u- Ituis fastened at I3 to the flywheel I5. The iiywhel andthe clutch are enclosed in a housing I1. The

driven or transmission shaft I9 is piloted into the end of the crankshaft at 2 I. Shaft I9 carries a hub 23 to which is secured through aknown cushioning device 25 a driven plate 21 having facings 29. Numeral3| is the pressure plateand C ment plate 31 having spaced tongues 39.Circumpressure plate, 'an improved location of the re-v gion of supportfor-the spring and of the regionl In the drawings accompanying thisdescription: i

(C1. 19a-cs) ferentially spaced relative to the tongues 39 of the plate31 are axial lugs 4| on the pressure plate, the lugs formed withhook-like ends 43. The spring 33 is of the Belleville washer type. It isconed as is usual with such resilient devices. It is formed with uniformthickness throughout. There are radially extending corrugationswherebythere are formed grooves 45 facing toward the flywheel and grooves 41 onthe opposite side. The corrugations have a progressively lessercircumferential extent from the outer periphery toward the Ycenteropening. The side wallsl near the center ,extend more nearly axially andstiien lthe plate resisting bending from its normal position `of rest,but the greater quantity of material in the walls makes for greaterresiliency in axial movementi The tongues 39 are received Within thegrooves 41 and the lugs 4I enter the grooves 45. lRotation of the-fiywheel and plate 31 is thus communicated to'spring 33 by the t of thetongues 39 in grooves 41 and the rotation of the spring is similarlytransmitted to the pressure plate by the walls of grooves 45 fitting thelugs 4I. By this construction frictionally sliding driving lugs be-`tween the pressure plate and flywheel are avoided. The taper of thegrooves prevents vradial slipping of the pressure plate and accommodatesits accurate centering.

. When the spring is assembled as described above and as shown, it isdistorted slightly and tensioned to bias the pressure plateinto clutchengaging position. The stressed condition may be appreciated by assumingthat if the cone were lWithout loading stress its apex would be somewhatto the left of the position shown inV Fig. 1, but the apex hasbeen movedsomewhat toward the right in the act of vassembling the spring with theparts 39 and 4 I With the parts so assembled the spring tension holdsthe pressure plate engaged owing to the distortion of the annular bandof the spring between the circles of contact dened by parts 39 and parts4 I. To -release thel clutch, one pulls the region at the apex stillfur'- ther to the right. Since the region at 39 is fixed, 4'

the pressureis relieved in thercircle of contact at 4I. To accomplishthis release, there .is used a sleeve 49 surroundingA shaft I9. At oneend of the the other end of sleeve 49 is a flange 53 adapted. to beengaged by a throw-out member 55. This may be an antifriction bearing ora body of graphite. The throw-out member is mounted i 'l a collar 51.The collar carries diametrically op posite trunnions 59, as iscustomary, which are envsleeve is a flange 5 I to engage and pull on theapex Y of the conical spring. There is no loading at this gaged by theforked ends ofa conventional lever -A 6I pivoted by any preferred formoffulcrum dc- 2 vice, such as '63, carried bythe housing |1. When thelever 6| isV rocked with a clockwise rotation, the sleeve is moved tothe right, the region of the spring cone adjacent its apex is similarlymoved but to provide means to positively move the pressure plate fromengagement .with the driven plate. For that purpose the'followingadditional" structure is used. A hairpin-like wire member designated asa whole by numeral 65 is formed with an inwardly bent part 61 locatedwithin the notch 43. On either side of part 61 thewire is carried upover the edges of the spring 33 from groove 45 and Jinto adjacentgrooves 41. Within grooves 41 the upper ends of the wire engage lugs 39at 10 from which the leg portions 69 extend throughout the length of thegrooves 41, engage the base of the groove throughoutI a part of thisextent and nally enter the rear end of openings 1| provided therefor onthe sleeve 49. When the clutch is being released and after the springload on the pressure plate is relieved, the

inner ends of legs 69 are picked up, whereuponl shaft 'and it alsohouses the clutch mechanism..

Secured at |09 to the flywheel is an annular plate formed with spacedforwardly directed extensions ||3 entering the rearwardly facing grooves||5 of a corrugated clutch-.spring |11 corresponding to the spring ofFig. l. Diifering 'from the, form iirst described, the extensions |f|3are radially inward of, instead of outwardly from, the pressure platelugs. 'The pressure plate is y the spring. AIn this form of theinventionthe Y spring is given an initial tension in assembling it relative tothe parts l I3 and ||9. This is ac-` complished by pressing the apexofthe cone y marked ||9 and is adapted to` grip the driven plate |2|secured to shaft |03. 'I'he pressure plate has lugs |23`Withn'otches|25, these lugs entering the forwardlybpening grooves `|21 of shapedspring toward the left. Since in this form the pressure plate ycontactisradially outwardly of region ||3, it will be appreciated that, in'assembling, the stress in the annular band between the pressure platecontact and the' contact with parts ||3 is such as to tend to move theapex region of the vconetoward the right from its position whenunloaded. The load is taken by the engagement between the pressure plateand driven plate. At the center is a sliding collar v| 33 adapted to bemoved to the left by a lever |29 acting on the collar by means of atrunnion block |3|. vThe collar |33 is formed with axial lugs |30,forming a shoulder for a ring |35 engaging the spring cone adjacent itsapex. As

the lever is rocked counterclockwise, the collar is moved to the leftand the coned spring further deected.` This action, unlike that ofthereleasing action shown by Fig. .51, 4does not tend t take the load oifthe pressure. plate. To positively move the pressure plate away from thedriven plate, a wire rod is used. It has legs |39 extending throughgrooves I|5 held therein by a. retainer |41 supported in apertures |49as is shown by Fig. 7. The legs then extend through and fulcrum in slots|45 formed on somewhat elongated parts H3 in those of the groovesthrough which the legs extend. Just beyond the outer periphery of theconical spring, thelegs are connected by loops |43 with a cross wire|4|. passing through the hook |25 of the lug |23.y Ro' tation of thelever |29 causes the legs |39 to rock about the walls of the slotsf'l45as a fulcrum and to pull the pressure plate from the driven-plate.

A third embodiment is shown in Figs. 8 and 9. In these figures 20| isthe ywheel and 203 is the clutch driven shaft. Numeral-205 is applied tothe driven plate and the pressure plate is marked 201. The anchor plate209 is secured at 2|| to the flywheel. The spring 2|3 is like the springof Fig. 4. The tongues 2|5 of the pressure plate enter the forwardlyopen corrugations and' lever, not shown, but like that of Fig. 4. Thisform 4also requires a hairpin pressure plate releasing device. To thatend U-shaped wires have their bights engaged in the hooked parts of thetongues 2|5 and their legs extend down through the corrugations,engaging in notches 22| of the anchor plate, substantially as in Fig. 4.Instead f a retaining device like |41 of Fig. 4, the 1egs e tend towardthe center vwhere they engage the throw-out member 2|9. The movement ofthe member 2|9.to the left causes the hairpin levers to hinge at 22| andpull the pressure plate away from the flywheel while it is givingadditional tension to the spring 2|3. To prevent the hairpin leverspressing the member 2|9. tothe right,

there is employed a tubular stamping 223 secured at 226 to part 2|9 atone end and its other end hooked over the edge of the spring `as at 225.

It will be seen,v therefore, that in this formt'4 the hairpin leverreactsagainst the ,throw-out' member instead of against a part like I 41carriedv by the'spring as in Fig. 4. change has been `found teconstitute a very satisfactory embodiment of the means to releasethejpressure plate which may be called the "pushf type of operatingmechanism. YThe hairpin lever is preferably bent at 221 to overcome itstendency to be thrown out by centrifugalv force. 'I'he stamping preventsrelative movement between part 2| 9 and the spring axially and alsoprevents relative rota-A the radially extending parts of the spring fromits contact with the anchor plate 209. In this way the hairpin' lever isnot required to bend duringclutch operation. Preferably, too, the threepoints of contact of the hairpin lever lie in a straight line, forming'an angle with the shaft axis' of about one-half the angular motion tion.The ratio of the arms of the hairpin lever in the opposite directionfrom its fulcrum point at 22| is substantially the same as-the ratio ofimparted on clutch disengagement tothereby rel duce slipping b etweenthe hairpin lever and the contact point.

'Ihe forms of the Iinvention are quite similar.

In each the long zero rate region isobtained by the corrugated structureof the spring element. In each case simplicity, reduction of cost andef- 'ferred to. Fig. 10 is the curve for a spring as transmission oftorque. the centering of the pressure plate, the prevention of radialmovement is accomplished. In each the desired spring characteristics areobtained by the depth and circumferential extent oi the corrugations.

The invention may be considered to be an improvement on the clutchengaging spring shown in patent to Almen et al., 2,045,557, and also asan improvement over the clutch shown by A. W. Gardiner in hisapplication Serial No. '118,- 896, Clutch, filed April 4, 1934. Therelatively long zerorate of this new spring as compared with the springshown by Patent 2,045,557, for example, has a very important advantagein clutch operation. This can be best explained by reference to thediagrams in Fig. 10 and Fig. 11. Fig. 11 shows the load-deflection curveof a normal Belleville spring like that of the patent regerein shown,one having the radial corrugaons. region of zero rate. On Fig. 10, bb'markithe longer region of Zero rate. The spring may be assumed to beconed when at rest and attened in exerting pressure. Ifthe clutchfacings bef come worn, it is less deectedf'toward a nat formation whenin clutch engaged position. The releasing mechanism must then begin itsoperation of deilecting the plate from a region oi' less deflection asfrom point a2 in Fig. 11, for ex ample.- It therefore operates partlyoutside the region of zero rate. 'This disadvantage may be avoided byusing a releasing pedal device having a lesser mechanical advantage,thereby keeping the spring action within 'the region of zero rate.structurally this may be accomplished by suitably spacing rather farapart radially the circles of contact of the spring with the springanchor and with the pressure plate. According to Fig.

V10, however, the long zero rate region makes it ,yielding means to biassaid members into frictional engagement, releasing mechanism toadditlonally stress said yielding means and release said clutch, saidyielding means being an axially coned annulus having a substantiallyzero rate throughout its normal working range, and formations in saidannulus to extend the/range of zero rate beyond the normal working rangewhereby an advantageous mechanical advantage is afforded for thereleasing mechanism.

2. In a clutch, driving and driven members,one of said members havingparts having relative axial movement to engage and disengage the clutch,an axially bowed and radially corrugated annular spring to directlyengage both said parts.

f3. In a crutch, driving and driven members, an abutment member carriedby one of said irst mentioned members, a pressure plate movable toeffect clutching engagement, a radially corrugated spring Aannuliis tomove said pressure plate,l

said pressure .plate and abutment plate having part seated'in opposedcorrugations.

On Fig. 11 a, a1 mark the limits of the 4. The invention dened by claim3 together with other means located in said corrugations to positivelymove said pressure plate in a clutch releasing direction.

5. For use in a clutch having driving and driven members, one of saidmembers having parts mounted for relative axial movement to grip theother member, a. metallic axially bowedspring annulus havingsubstantially radial corrugations to form oppositely facing grooves,said parts ex tending within said grooves whereby torque is transmittedbetween said parts.

A6. For use with a clutch having an axially xed abutment and a pressureplate movable to eiect clutch engagement., an annular spring plate tomove said pressure plate, said spring plate having radial corrugationsoflesser Width from its outer to its inner periphery.

7. The invention dened by claim 6, the spring engaging parts of thepressure plate and of the abutment plate being of unequal radialdistance from the axial center of the clutch whereby the spring bias toeffect clutch engagement is effected by a distortion of said annularspring.

8. In a clutch, a driving member, a driven member, a pressure platemovable axially to grip the driven member between itself and the drivingmember, said driving member having a spring anchorage, a normallystressed Belleville spring having alternating oppositely disposed radialcorrugations, said anchorage and said pressure plate having radiallyspaced circular regions of contact withsaidcorrugations, and means toadlditionally stress said spring to insure clutch releasing action.

9. The invention deilned by claim 8, the region of contact between theanchorage and spring being radially less than the region of contact ofthe spring with the pressure plate.

10. The invention defined by claim 8, the `region of contact between theanchorage and spring being radially less than the region of ofntact ofthe spring with thepressure plate together with lever means moved bysaid clutch releasing means pivoted on said anchorage and operable towithdraw said pressureplate.

11. In a clutch mechanism, a driving member,

` a driven member, Belleville spring means yieldingly urging the anddriven members into driving engagement, said spring means having aninherent substantially zero rate within its operating range, and saidyielding means having radial corrugations to abnormally extend theregion of zero rate to permit clutch operation with a relatively highmechanical advantage.

said spring, and means to additionally stress said spring to insureclutch releasing action, the region of contact between the anchorage andspring being radially less than the region of contact of the spring withthe pressure plate.

JOHN O. ALMEN. VHENRY J. KIRSCHNER.

